The invention relates to irrigation apparatus and particularly to such apparatus which includes pulsators. The invention is especially useful with respect to dripper-type irrigation apparatus, and is therefore described below with respect to this application.
The growing use of artificial bedding in nurseries and open fields, and particularly the use of soils with very low water retaining capacity, have created a need for irrigation apparatus having very low discharge rates, of the order 0.1-0.3 liters per hour. Such low discharge rates allow the water to travel by capillary action, and thus increase the water retaining capacity of the plant growing media. Providing low water discharge rates also effects significant savings of water and fertilizer. The use of pulsator devices, such as described in U.S. Pat. Nos. 4,781,217 and 4,949,747 of Peretz Rosenberg or 4,955,539 of G. Ruttenberg, have been found to allow lower discharge rates to be used permitting significant savings of water and fertilizer.
One recent technique for using pulsators to lower the water discharge rate, described in U.S. Pat. No. 5,353,993, includes a feeder line for supplying the water and a dripper line connected to the feeder line via a plurality of spaced pulsator devices. However, using two separate lines is expensive and cumbersome, and moreover, requires drippers with small passages.